I arrived at the same conclusion, and just double- and triple-checked myself that it makes sense. It seems to me that #3 has great reading comprehension, but wanted to make sure he didn't make a mistake...
And you guys are assholes, a simple "yes" should suffice.
Edit: I guess you guys meant that the GIRLFRIEND/WIFE had an affair with the FATHER, and not the other way around... but seriously, that could be an English-as-a-second-language mistake.

There is a line between sarcasm and being a dick (unless you know the person). Hell, just the fact that you state people "don't understand sarcasm" after the neg comments and thumbs down puts you in the latter category. Obs, dude's question was legit. Side-by-side, I'd take him over d-bag...I mean "sarcastic" any day. I'm guessing that "Gearhead" is the name on your birth certificate, huh?

#8 I think it really depends on how old the child is. If the child is older OP may already have an emotional attachment and it would be very damaging for the child on a psychological level I'm sure, but if the child is still just an infant then I say yeah cut your losses and move on with your life. Let them figure it out.
Plus I hope OPs father isn't in a relationship, that adds a whole other level of complications.

The way the FML is worded that doesn't seem likely. He said the paternity test proved what he thought, so he obviously had doubts the kid was his and just had it confirmed. When you are suspecting your son isn't yours and is actually your brother kinda seems like you leaning more towards the not raising the kid.